Radio communication terminal and base station assignment method

ABSTRACT

There is provided a radio communication terminal that can reduce power consumption by a radio communication terminal when searching for a radio base station apparatus that is to be connected to the radio communication terminal, and that can reduce the time it takes to search for the radio base station apparatus. The radio communication terminal communicates with a radio base station apparatus through a network in which a plurality of radio communication schemes are present for use in a mixed manner, and includes a processor and an antenna. The processor acquires location information of the radio communication terminal, and locates a connection base station as a radio base station apparatus that communicates user data with the radio communication terminal, among a plurality of the radio base station apparatuses, based on the location information of the radio communication terminal and on information that is the history of communication with the radio base station apparatus in every location in which the radio communication terminal is present. Through the antenna, the user data is communicated between terminal itself and the connection base station.

TECHNICAL FIELD

The present disclosure relates to a radio communication terminal and abase station assignment method.

BACKGROUND ART

When a terminal performs radio communication, there is a need todetermine a radio base station to which the terminal makes a radioconnection and to determine a radio frequency (a radio channel) that isused by the terminal for radio communication. In the related art, aradio base station selection apparatus is known that searches for theradio base station and the radio channel for selection using active scanor passive scan (for example, PTL 1).

The radio base station selection apparatus creates a connectioncandidate AP list in which identification information of and a receptionlevel of the radio base station are associated with each other for everyradio channel. The radio base station selection apparatus selects oneradio base station that has a reception level which exceeds apredetermined threshold and that has identification information with ahigh priority level, and a corresponding channel from the connectioncandidate AP list. The radio base station selection apparatus performsprocessing that makes a connection to the selected radio base station onthe selected radio channel.

Furthermore, in recent years, a heterogeneous network in a radiocommunication system in which the terminal and the radio base stationapparatus is connected to a network has been under study (for example,NPL 1 to NPL 3).

CITATION LIST Patent Literature

PTL 1: Japanese Patent Unexamined Publication No. 2010-193088 Non-PatentLiterature

NPL 1: NAKAO Seigo, YAMAMOTO Tetsuya, OKASAKA Shozo, SUZUKI Hidetoshi,“Activities on heterogeneous networks for 5G: C-plane/U-plane SplittingControl in Heterogeneous Networks”, IEICE technical report, p 83-88,October 2014

NPL 2: SAMPEI Seiichi, “A Study on Technical Directions of WirelessAccess Networking for 5G Cellular Systems”, IEICE technical report,P153-P158, October 2014

NPL3: “DoCoMo 5G White Paper—Required Conditions and Technical Conceptsin 5G Radio Access After 2020”, NTT DoCoMo, P1-14, September 2014

SUMMARY OF THE INVENTION

When a radio base station selection apparatus that is disclosed in PTL 1finds application in processing that searches for a radio base stationand a radio frequency in a heterogeneous network, a terminal needs tosearch for the radio base station using a plurality of types of radiocommunication schemes. For this reason, it is difficult to reduce powerconsumption by the terminal when searching for the radio base station,or it is difficult to reduce the time that it takes to search for theradio base station.

The present disclosure, which is provided in view of the situationdescribed above, provides a radio communication terminal and a basestation assignment method that can reduce power consumption by a radiocommunication terminal when searching for a radio base station apparatusthat is to be connected to the radio communication terminal, and canreduce the time that it takes to search for the radio base stationapparatus.

The radio communication terminal in the present disclosure communicateswith a radio base station apparatus through a network in which aplurality of radio communication schemes are present for use in a mixedmanner. The radio communication terminal includes a processor and anantenna. The processor acquires location information of the radiocommunication terminal, and locates a connection base station as a radiobase station apparatus that communicates user data with the radiocommunication terminal, among a plurality of the radio base stationapparatuses, based on the location information of the radiocommunication terminal and on information that is the history ofcommunication with the radio base station apparatus in every location inwhich the radio communication terminal is present. Through the antenna,the user data is communicated between terminal itself and the connectionbase station.

According to the present disclosure, power consumption by the radiocommunication terminal when searching for the radio base stationapparatus that is to be connected to the radio communication terminalcan be reduced, and the time it takes to search for the radio basestation apparatus can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating an example of a configurationof a radio communication system according to a first embodiment.

FIG. 2 is a block diagram illustrating an example of a configuration ofa terminal according to the first embodiment.

FIG. 3 is a schematic diagram illustrating an example of historydatabase T1.

FIG. 4 is a schematic diagram illustrating an example of historydatabase T2.

FIG. 5 is a flowchart illustrating an example of an operation that isperformed when a connection candidate base station is located by a radiocommunication system.

FIG. 6 is a flowchart illustrating an example of an operation that isperformed when a radio frequency that is used by a terminal is derivedby the radio communication system.

FIG. 7 is a schematic diagram illustrating an example of a locationrelationship between a base station and the terminal.

DESCRIPTION OF EMBODIMENTS

Embodiments will be described in detail below, suitably with referenceto the drawings. However, in some cases, the descriptions that are ingreater detail than is necessary are omitted. For example, in somecases, a detailed description of a matter is already known, or arepeated description of substantially the same configuration is omitted.This serves to prevent the following descriptions from beingunnecessarily redundant and to provide an easy understanding to a personof ordinary skill in the related art. The accompanying drawings and thefollowing descriptions are provided in order for a person of ordinaryskill in the related art to sufficiently understand the presentdisclosure, but this is not intended to limit subjects that are setforth in claims.

First Embodiment

[Configuration and the Like]

FIG. 1 is a schematic diagram illustrating an example of a configurationof radio communication system 10 according to a first embodiment. Radiocommunication system 10 includes one or more terminals 100 and one ormore base stations 200. Terminal 100 and base station 200 are connectedto each other through a radio circuit.

Radio communication system 10 is a heterogeneous network in which basestation 200 to which terminal 100 has to make a connection complies withvarious radio specifications. Terminal 100 communicates with basestation 200. In the heterogeneous network, base stations 200 that havedifferent radio communication schemes (for example, a Radio AccessTechnology (RAT)) or different cell radii are present in a fixed manner.In the heterogeneous network, for example, not only are a plurality oftypes of radio specifications present in a mixed manner, but also basestations 200 that have different cell radii overlap in area. The RAT,for example, includes pieces of information on radio communicationspecifications and on radio frequencies.

The heterogeneous network may not be a network that is of a C/Useparation type, and may be a network that is of a C/U separation type.In the present embodiment, an example of the network that is not of aC/U separation type is given. More precisely, an example in which inradio communication system 10, communication relating to control dataand communication relating to user data are performed by same basestation 200 is given.

Base station 200 includes macro cell base station 200A and small cellbase station 200B. Terminal 100 communicates the control data andcommunicates the use data with any one of macro cell base station 200Aand small cell base station 200B. The control data includes datarelating to Control (C)-Plane. The user data includes data relating toUser (U)-Plane. Pieces of user data, for example, include image data(for example, a moving image or a still image) and audio data, and caninclude data of which a size is larger in terms of data mount.

C-plane is a communication protocol for communicating control data forcall connection or radio resource assignment in radio communication.U-plane is a communication protocol for actually performingcommunication (for example, video communication, audio communication, ordata communication) using the assigned radio resource between terminal100 and base station 200.

A cell radius of macro cell base station 200A, for example, ranges from1 km to several km, and is comparatively great. A RAT that is employableby macro cell base station 200A, for example, is one type (for example,LTE). The cell radius is equivalent to the maximum transfer distance ofbase station 200.

A cell radius of small cell base station 200B, for example, ranges from10 m to 100 m, and is comparatively small. There are many RATs that areemployable by small cell base station 200B, and a plurality of types ofRATs are present. For example, it is also considered that the cellradius may be equal to or greater than 100 m in a mountain area, adesert region, and a forest area, and that the cell radius is greaterthan the cell radius of macro cell base station 200A. More precisely, atthis point, when it comes to distinction between macro cell base station200A and small cell base station 200B, the cell radii are not taken intoconsideration in terms of size.

FIG. 1 illustrates that “MBS” denotes macro cell base station 200A, that“SBS” (Δ) denotes small cell base station 200B, and that “T” denotesterminal 100. A line that surrounds macro cell base station 200A denotesan image of a range where communication by macro cell base station 200Ain question is available. A line that surrounds small cell base station200B denotes an image of a range where communication by small cell basestation 200B in question is available. A range where communication bybase station 200 is available, for example, is determined according to alocation and a cell radius of base station 200.

Terminal 100 and base station 200 set RATs that are used forcommunication, from RATs (for example, radio communicationspecifications and radio frequencies) that are employed by theapparatuses in question, respectively, and perform radio communicationaccording to the RATs that are set. It is possible that each of terminal100 and base station 200 employ one or more RATs.

Radio communication specifications, for example, includes Long TermEvolution (LTE), Local Area Network (Wireless LAN), Digital EnhancedCordless Telecommunication (DECT), Third Mobile Communication System(3G), Fourth Mobile Communication System (4G), and Fifth MobileCommunication System (5G).

RATs include RAT 1 to RAT 5, as pieces of specific information. RAT 1,for example, is LTE in which a radio frequency band is in a range of 700HMz to 3 GHz. RAT 2, for example, is LTE-Advanced in which a radiofrequency band is in a range of 15 GHz. RAT 3, for example, is WirelessLAN communication in which a radio frequency band in a range of 5 GHz.RAT 4, for example, is a radio communication scheme for a radiofrequency band of 15 GHz, and is a fifth mobile communication scheme.RAT 5, for example, is a radio communication scheme (for example, amillimeter wave communication) (for example, WiGig) for a radiofrequency band of 60 GHz.

FIG. 2 is a block diagram illustrating an example of a configuration ofterminal 100. Terminal 100 includes processor 150, memory 160, GlobalPositioning System (GPS) antenna 101, GPS receiver 102, transmissionantenna 108, and reception antenna 109.

Processor 150 performs various processing operations or controls incooperation with memory 160. Specifically, processor 150 realizes afunction of each of the following units by executing a program that isretained in memory 160. Units include the location information generator103, base station locator 104, radio resource assignment manager 105,transmission packet generator 106, radio transmitter 107, radio receiver110, and reception packet decoder 111.

For example, various pieces of data, information, programs are stored inMemory 160. Furthermore, history databases T1 and T2 are stored inmemory 160. Memory 160 may be built into processor 150. Memory 160 mayinclude not only a primary memory device, but also a secondary memorydevice.

FIG. 3 is a schematic diagram illustrating an example of historydatabase T1. The history database T1 retains information, which is thehistory of communication (the record of communication) with a connectionbase station in every location in which terminal 100 is present. Theconnection base station is base station 200 that is connected toterminal 100 for communication. History database T1, for example,retains information relating to terminal 100, and information that isthe history of communication with the connection base station during apast fixed period of time.

The information relating to terminal 100 includes location information(for example, longitude and latitude) of terminal 100, andidentification information (for example, an area number) on an area interminal 100 that stays. The information that is the history ofcommunication includes identification information (for example, BS #6)of the connection base station, a RAT (for example, LTE) that isemployed by the connection base station, and information on the numberof times of communication (the number of times of radio connection) withthe connection base station and an amount of communication (an amount ofcommunication data) relating to the communication with the connectionbase station.

Pieces of location information of terminal 100 are categorized by anarea number and are managed. Furthermore, the history of communicationbetween terminal 100 and the connection base station is managed andupdated on a pre-area basis. The area in which terminal 100 staysrepresents a predetermined range where terminal 100 is present, and forexample, is set to a size of 50 meters (m)×50 m. Furthermore, in an areathat is heavily populated with base stations 200, an area of the area isset to be comparatively small, and for example, is set to a size of 20m×20 m. Furthermore, in an area that is sparsely populated with basestations 200, an area of the area is set to be comparatively large, andfor example, is set to a size of 200 m×200 m.

FIG. 4 is a schematic diagram illustrating an example of historydatabase T2. For every connection base station, history database T2retains information that is the usage history of a radio frequency thatis used by terminal 100 to communicate with the connection base station.The history database T2, for example, retains information relating tothe connection base station and information that is the usage history ofa radio frequency for a past predetermined period of time.

The information relating to the connection base station includes theidentification information of the connection base station (for example,BS #1), and information on the RAT that is employed by the connectionbase station. The information that is the usage history includesinformation on a radio frequency that is used for the communication withthe connection base station, and the information on the number of timesof communication with the connection base station and the amount ofcommunication relating to the communication with the connection basestation.

History databases T1 and T2 may be individually provided for uplink 21and downlink 22, and may be provided in a shared manner. Furthermore,RATs that base station 200 is capable of employing, which are retainedin history databases T1 and T2, is a RAT that terminal 100 is alsocapable of employing.

Uplink 21 is a radio link from terminal 100 to base station 200.Downlink 22 is a radio link from base station 200 to terminal 100. Radiolinks broadly include ones in various public circuit, a portabletelephone circuit, and a wide-area broadband radio circuit, and thelike.

GPS receiver 102 receives the location information (for example,information on latitude, longitude, and altitude) of terminal 100 fromGPS satellite 50 through GPS antenna 101. The location informationindicates a current location of terminal 100.

Based on the location information from GPS satellite 50, and the like,the location information generator 103 generates the locationinformation of terminal 100.

Referring to history database T1, base station locator 104 locates (forexample, calculates) candidate base station 200 (hereinafter alsoreferred to a “connection candidate base station”) that is a targetwhich is wirelessly connected by terminal 100. Specifically, based oninformation that is retained in history database T1 and the locationinformation of terminal 100 (for example, current location informationthat is obtained by the GPS), base station locator 104 locates theconnection candidate base station.

In this case, base station locator 104, for example, determines an areato which a current location of terminal 100 belongs. Referring tohistory database T1, base station locator 104, for example, determinesbase station 200 that has the largest amount of communication relatingto communication with terminal 100 in the area to which terminal 100belongs, as the connection candidate base station. Furthermore,referring to history database T1, base station locator 104, for example,determines base station 200 that has the greatest number of times ofcommunication with terminal 100 in the area to which terminal 100belongs, as the connection candidate base station. Furthermore, basestation locator 104 may determine a plurality of base stations 200 thathave the history of communication, as connection candidate basestations. In this case, base station locator 104 may set priority levelsof the connection candidate base stations in order of decreasing thenumber of the histories of communication.

Radio resource assignment manager 105 acquires information of theconnection candidate base station from base station locator 104. Theinformation of the connection candidate base station, for example,includes information relating to which is a radio communicationspecification that is used between the connection candidate base stationand terminal 100, or information relating to a frequency band. Theinformation of the connection candidate base station may includeinformation on the priority level of the connection candidate basestation.

Radio resource assignment manager 105 performs management using piecesof information in history database T2, in such a manner that a radioresource which is used for the communication with the connection basestation is assigned in cooperation with the connection base stationamong the connection candidate base stations. The radio source, forexample, includes a radio frequency that is used for communication and aResource Block (RB) in a radio frequency. The RB, for example, indicatesa unit of radio frequency assignment, which results from dividing aradio frequency (for example, a subcarrier frequency) along thefrequency axis and the time axis (for example, a time slot).

Referring to history database T2, radio resource assignment manager 105derives an assignment candidate for a radio frequency that is used forthe communication with the connection base station, based on the usagehistory of the radio frequency that is used in the past by terminal 100.

For example, radio resource assignment manager 105 determines a radiofrequency that appears frequently (more often) in the usage history, asthe assignment candidate for the radio frequency that is to be assignedto communication in uplink 21. The radio frequency that appearsfrequently in the usage history, for example, may be a radio frequency,an amount of accumulated communications on which is the largest inhistory database T2, and may be a frequency, an amount of communicationdata on which is a predetermined amount or larger. As the candidates forthe radio frequency, there may be a plurality of candidates ranging froma candidate having a high priority level to s candidate having a lowpriority level.

Radio resource assignment manager 105 reports to the connection basestation the assignment candidate for the radio frequency. In theconnection base station, a RB assignment situation in the radiofrequency is searched for, based on the assignment candidate for theradio frequency, which is reported from terminal 100, it is determinedwhether or not a RB is available for assignment, and if the RB isavailable for assignment, a result of determination of which radioresource has to be used for data communication is transmitted toterminal 100. Referring to the result of the determination, radioresource assignment manager 105 performs the data communication. Thedetermination result, for example, includes information on whether ornot the RB is available for assignment, or information on the RB in theradio frequency that is assigned in a case where the RB is available forassignment.

Based on the result of the determination, radio resource assignmentmanager 105 assigns a RB that is not assigned in the radio frequencywhich is used for the communication with the connection base station.

Furthermore, radio resource assignment manager 105 may designate notonly the assignment of a RB and Adaptive Modulation and Coding (AMC).

In a case where it is impossible that the radio resource in the radiofrequency that is the assignment candidate is assigned, radio resourceassignment manager 105 may change the radio frequency, and may newlyselect a radio frequency from among radio frequencies that are otherassignment candidates. Furthermore, in a case where the radio frequencyin which the RB that is available for assignment to the connection basestation is not present, radio resource assignment manager 105 may changethe connection base station, and may newly select a connection candidatebase station from among other connection base stations.

Furthermore, radio resource assignment manager 105 acquires theinformation that is the usage history of the radio resource, fromtransmission packet generator 106 or reception packet decoder 11. Theinformation that is the usage history, for example, includes theinformation on the radio frequency that is used for the communicationbetween terminal 100 and the connection base station, and theinformation on the amount of communication that takes place duringcommunication that uses the radio frequency. Radio resource assignmentmanager 105, for example, performs addition of the amount ofcommunication that is included in the information on the usage history,for the radio frequency in history database T2, which is consistent withthe radio frequency that is included in the acquired information on theusage history, and updates the information that is retained in historydatabase T2.

Radio resource assignment manager 105 sends information on the radioresource that is assigned, more precisely, information on the radiofrequency and the RB that is used for the communication with theconnection base station, to radio transmitter 107 or radio receiver 110.In this case, radio resource assignment manager 105 sends information ona radio resource for uplink 21, which is assigned, to radio transmitter107. Furthermore, radio resource assignment manager 105 sendsinformation on a radio resource for downlink 22, which is assigned, toradio receiver 110.

Transmission packet generator 106 generates a packet (transmissionpacket) that is to be transmitted to base station 200. The transmissionpacket includes data on uplink 21. The data (control data or user data)on uplink 21 is obtained, for example, from memory 160, an externaldevice (not illustrated), such as a storage device, and various softwareprocessors (not illustrated).

Furthermore, transmission packet generator 106 sends the informationthat is the usage history of the radio resource relating tocommunication of the transmission packet, to radio resource assignmentmanager 105.

Radio transmitter 107 transmits the transmission packet to theconnection base station that is designated by radio resource assignmentmanager 105 through uplink 21 and transmission antenna 108, using theassigned radio resource.

Radio receiver 110 receives the packet (reception packet) from theconnection base station through downlink 22 and reception antenna 109,using the radio resource that is assigned by radio resource assignmentmanager 105.

Reception packet decoder 111 decodes the reception packet, and obtains adecoded data. The decoded data includes data on downlink 22. The data(control data or user data) on downlink 22 is passed along, for example,to memory 160, an external device (not illustrated), such as a storagedevice or a display device, and various software processors (notillustrated).

Furthermore, in some cases, information of the connection candidate basestation that is selected with a known method is included in the data ondownlink 22. The information of the connection candidate base station issent to radio resource assignment manager 105.

Furthermore, the data on downlink 22 includes control informationrelating to the radio resource assignment. The control information issent to radio resource assignment manager 105. For example, adetermination result of determining whether or not the RB is availablefor assignment by the connection base station is included in the controlinformation.

Furthermore, reception packet decoder 111 sends the information that isthe usage history of the radio resource relating to communication of thereception packet, to radio resource assignment manager 105.

[Operation and the Like]

Next, an example of operation of radio communication system 10 isdescribed.

FIG. 5 is a flowchart illustrating an example of an operation that isperformed when terminal 100 locates the connection candidate basestation.

Radio receiver 110 or radio transmitter 107 determines whether or notthere is present a connection request (S11). Connection requests, forexample, include a connection request from terminal 100 to base station200, and a connection request from base station 200 to terminal 100. Forexample, in a case where terminal 100 acquires a moving image in acontent server and reproduces the acquired moving image, the connectionrequest from terminal 100 to base station 200 is made. For example, in acase where a call from another terminal to terminal 100 is made, theconnection request form base station 200 to terminal 100.

GPS receiver 102, for example, detects (acquires) the locationinformation (information on a current location) of terminal 100 from GPSsatellite 50 (S12).

Referring to history database T1 (S13), base station locator 104determines whether or not the current location that is acquired in GPSreceiver 102 is included in area information. In a case where an areathat is included in the current location is present, base stationlocator 104 determines whether nor base station 200 is present which hasthe history of communication showing that communication is performed, inthe area, with an amount of communication which is a predeterminedamount of communication or larger (S14).

In a case where an area in which the current location of terminal 100 isincluded is not present in history database T1, or in a case where basestation 200 that has the history of communication described above is notpresent, base station locator 104 searches for (conducts a cell searchof) base station 200 (S15) using a known method. In this case, based ona result of the search for base station 200 that stays in the vicinityof terminal 100, base station locator 104 determines a connectioncandidate base station.

In the known method, for example, base station locator 104 searches forbase stations 200 that use RATs 1 to 5, in this order, and radiotransmitter 107 notifies a predetermined base station of a result of thesearch. The predetermined base station selects a connection candidatebase station according to the notified result of the search, andtransmits information of the connection candidate base station toterminal 100. Base station locator 104 acquires the information of theconnection candidate base station from the reception packet that isreceived by radio receiver 110 and is decoded by reception packetdecoder 111, and makes the determination as the connection candidatebase station.

At this point, as the known method, the example is provided in which theresult of the cell search is notified to a predetermined base stationand the predetermined base station transfers the information of theconnection candidate base station to terminal 100. Instead, terminal 100may determine the connection candidate base station on its own based onthe result of the cell search without notifying the predetermined basestation of the result of the cell search.

In a case where in S14, base station 200 that the history ofcommunication described above is present, base station locator 104determines base station 200 as a connection candidate base station(S16). Only one connection candidate base station may be determined, anda plurality of connection candidate base stations may be determined.Furthermore, in a case where the connection candidate base station isdetermined, base station locator 104 may set priority levels of theplurality of connection candidate base stations. For example, basestation locator 104 sets a priority level of a connection candidate basestation that has a large amount of communication, to be high.

When the connection candidate base stations are determined, radioresource assignment manager 105 determines the connection base stationfrom the connection candidate base stations. In a case where oneconnection candidate base station is determined, radio resourceassignment manager 105 selects base station 200 as a connection basestation.

Furthermore, in a case where a plurality of determined connectioncandidate base stations are present, radio resource assignment manager105, one is selected from among the plurality of determined connectioncandidate base stations. For example, radio resource assignment manager105 may select a connection candidate base station that has a largeamount of communication in the past communication, as a connection basestation.

Furthermore, radio resource assignment manager 105 assigns a radioresource that is used for the communication with the connection basestation. The assignment of the radio resource, as will be describedbelow with reference to FIG. 6, may be performed based on informationthat is retained in history database T2, and may be performed with aknown method. As the known method, for example, channel quality (anamount of interference) of every radio frequency is measured by terminal100 or the connection base station, and a radio frequency that is to beused for the communication between terminal 100 and the communicationwith the connection base station is assigned.

Radio transmitter 107 or radio receiver 110 communicates user databetween terminal 100 and the connection base station (S17). For example,transmission packet generator 106 generates the transmission packet thatincludes the data on uplink 21. Radio transmitter 107 wirelesslytransmit the transmission packet to the determined connection basestation. Furthermore, for example, radio receiver 110 wirelesslyreceives the reception packet from the determined connection basestation. Reception packet decoder 111 decodes the reception packet andobtains the data on downlink 22.

Transmission packet generator 106 or reception packet decoder 111updates history database T1 according to the history of communication(S18).

For example, transmission packet generator 106 updates history databaseT1 according to the transmission history of the transmission packet. Inthis case, in a case where terminal 100 performs communication in S17after the processing in S15, transmission packet generator 106 newlywrites a terminal location at the time of the radio transmission, anumber of an area to which the terminal location belongs, andinformation on the number of times of communication or the amount ofcommunication in the area, to history database T1. Furthermore, in acase where terminal 100 performs communication S17 after the processingin S16, transmission packet generator 106 updates history database T1with the information on the amount of communication or the number oftimes of communication in the area to which the terminal location at thetime of the radio transmission belongs.

For example, reception packet decoder 111 updates history database T1according to the reception history of the reception packet. In thiscase, in a case where terminal 100 performs communication in S17 afterthe processing in S15, reception packet decoder 111 newly writes aterminal location at the time of the radio reception, a number of anarea to which the terminal location belongs, and the number of times ofcommunication or the amount of communication in the area, to historydatabase T1. Furthermore, in a case where terminal 100 performscommunication S17 after the processing in S16, reception packet decoder111 updates history database T1 with the information on the amount ofcommunication or the number of times of communication in the area towhich the terminal location at the time of the radio reception belongs.

The communication in S17 may be either a bi-directional communication orany one of the transmission and the reception. Therefore, the updatingof history database T1 in S18 may be performed at the time of either thetransmission or the reception.

In this manner, in a case where the history of communication betweenterminal 100 and any base station 200 in an area to which terminal 100belongs when performing communication is equal to or larger than apredetermined reference, terminal 100 does not need to search for (toconduct the cell search of, or discover) base station 200 with a knownmethod. More precisely, terminal 100 does not need to sequentially scanthe radio communication schemes (the RATs) that are employable, and tosearch base station 200 that is positioned in the vicinity of terminal100. In this case, terminal 100 does not need to make as many cellsearches as the number of RATs that are present in the heterogeneousnetwork. For reason, terminal 100 can reduce processing load and theprocessing time for searching for base station 200 that is a connectiondestination.

On the other hand, in a case where the history of communication betweenterminal 100 and any base station 200 in an area to which terminal 100belongs when performing communication is neither equal, nor larger thanthe predetermined, more precisely, in a case where the number of thehistories of communication is not sufficiently great, terminal 100searches for base station 200 with a known method. In this case, it isconsidered that a state results where a radio frequency or a radioresource is selected for communication without sufficiently segregatingradio frequencies or radio resources that are used by each base station200 and without sufficiently taking into account the past history. Incontrast, terminal 100 does not perform selection of the connectioncandidate base station that is based on the past history ofcommunication. Thus, the precision of selection of the connectioncandidate base station can be improved and the precision of selection ofthe connection base station can be improved.

FIG. 6 is a flowchart illustrating an example of an operation that isperformed when a radio frequency that is used by terminal 100 isassigned. In FIG. 6, it is assumed that the assignment of the radioresource, the selection of the assignment candidate for the radioresource, and the communication of the user data are performed in anyone of uplink 21 and downlink 22.

First, when the connection request from terminal 100 to base station200, or the connection request from base station 200 to terminal 100occurs, base station locator 104 selects the connection base station(S21). A method of selection the connection base station (a locationmethod) may be the method that is described with reference to FIG. 5,and may be a known method.

Referring to history database T2 (S22), radio resource assignmentmanager 105 selects a radio frequency, the frequency of whose use ishigh (the number of the histories of whose use is great) as theassignment candidate for the radio frequency, as is the case when anamount of communication is large in the selected connection base station(S23).

With the method described above, radio resource assignment manager 105can know whether or not it is possible that a RB is assigned in theassignment candidate for the radio frequency (S24). More precisely, whenthe assignment candidate for the radio frequency is selected, terminal100 shares information on the assignment candidate for the radiofrequency with the connection base station. The connection base stationchecks a situation where a RB in the radio frequency is assigned toterminal 100 that belongs to the connection base station, and determineswhether or not the RB in the radio frequency is assigned to terminal100. The connection base station feedbacks a result of the assignment ofthe RB in the radio frequency to terminal 100. In a case where it ispossible that the RB in the radio frequency is assigned, the connectionbase station assigns the RB to terminal 100, and thus communicates datawith terminal 100.

In S24, in a case where it is impossible that the RB in the selectedradio frequency is assigned, radio resource assignment manager 105determines whether or not a priority level of the radio frequency thatis decided to be the assignment candidate is the lowest (S25).

For example, in a case where processing in S25 is the first one, forexample, the priority level of the radio frequency that is theassignment candidate is the highest, and whenever the number of timesthat the processing in S25 is performed, the priority level of the radiofrequency that is the assignment candidate is lowered.

In S25, in a case where the priority level of the radio frequency thatis decided to be the assignment candidate is not the lowest, radioresource assignment manager 105 selects a radio frequency of which apriority level is lower than that of the radio frequency in question,more precisely, a radio frequency of which a priority level is the nextmost one, as an assignment candidate (S26). Then, terminal 100 proceedsto processing in S24.

In a case where in S25, the priority level of the radio frequency thatis decided to be the assignment candidate, based on the information ofthe connection candidate base station from base station locator 104,radio resource assignment manager 105 determines whether or not theconnection candidate base station is present in another area (S27). In acase where the connection candidate base station is present in anotherarea, terminal 100 proceed to S21.

In a case where the connection candidate base station is not present inanother area, the connection request described above results in a callfailure or enters a waiting state, without the radio resource beingassigned in response to the connection request (S28). Terminal 100 endsthe processing in FIG. 6.

In a case where it is possible in S24 that the RB in the radio frequencyis assigned, radio resource assignment manager 105 assigns the RB in theradio frequency, which is allocable. Radio transmitter 107 or radioreceiver 110 communicates user data with the connection base stationusing the RB in the radio frequency, that is assigned (S29).

When the user data is communicated, the information on the amount ofcommunication that takes place during communication is sent to radioresource assignment manager 105. For example, transmission packetgenerator 106 sends the information on the amount of communication ofthe transmission packet that is transmitted, to radio resourceassignment manager 105. For example, reception packet decoder 111 sendsthe information on the amount of communication of the reception packetthat is received, to radio resource assignment manager 105. Radioresource assignment manager 105 updates the history of communication onthe radio frequency that is used in the connection base station whichperforms communication, in history database T2 (S30). Terminal 100 endsthe processing in FIG. 6.

In this manner, terminal 100 can assign a radio frequency that has a lowlikelihood of communication interference's occurring, using theinformation that is the usage history of the radio frequency in thepast, which relates to the communication of the user data. Furthermore,in a case where it is impossible that the RB in the radio frequency thatis the assignment candidate is assigned, because a RB in another radiofrequency is assigned or the connection base station is changed, thereis a high likelihood that terminal 100 will be able to discover a radiofrequency for communication user data. More precisely, terminal 100 canimprove the efficiency of assignment of or the efficiency of usage of aradio resource. Therefore, terminal 100 can segregate the radiofrequencies that are used for the communication with base station 200,in an autonomous and distributive manner.

[Effects and the Like]

Terminal 100 stores history database T1 that results from associating alocation of terminal 100 itself and information that is the history ofcommunication by base station 200 that has the history of communication,with each other. Terminal 100 stores history database T1 that resultsfrom associating a location of terminal 100 itself and information thatis the history of communication by base station 200 that has the historyof communication, with each other. Accordingly, terminal 100 can take aninitiative to determine base station 200 to which terminal 100 itselfhas to make a connection, without base station 200 retaining historydatabase T1.

Furthermore, terminal 100 can reduce the need to perform excessive cellsearch processing for specifying the connection candidate base station,can reduce power consumption by terminal 100 itself, and can reduce thetime it takes to search for the connection candidate base station.

Furthermore, in a connection base station that performs communicationfrequently, because an amount of data that is accumulated in historydatabase T1 is large, there is a high likelihood that the connectionbase station will be selected as a connection candidate base station.More precisely, because the connection base station is selected based onthe history of communication showing the successful communication, thelikelihood that a connection base station which has a high likelihood ofthe communication connection being successful will be selected isincreased. There is a high likelihood that the communication with theconnection base station which performs communication frequently in thepast will be successful in the future. Therefore, terminal 100 canimprove the precision of communication in the communication with theconnection base station.

In a case where a location in which communication by terminal 100 isperformed, more precisely, in a case where the location of terminal 100is not too frequently, a method of specifying the connection candidatebase station or the connection base station according to the presentembodiment is particularly effective. As terminal 100 in this case, forexample, an electronic billboard, a vending machine, or a constructionmachine is considered. As the communication in this case, for example, aMachine to Machine (M2M) communication, in-home communication, orin-office communication is considered.

Terminal 100 stores history database T2 in which the information that isthe usage history of the radio frequency relating to the communicationwith the connection base station. Referring to history database T2,terminal 100 assigns a radio resource (a radio frequency or a RB) whenthe connection request occurs. Accordingly, terminal 100 can take aninitiative to determine a radio resource that has to be used forcommunication, without base station 200 retaining history database T2.

Furthermore, terminal 100 can reduce the need to perform detectionprocessing of an enormous amount of channel quality information fordetermining an environment in which a radio frequency is used.

It is indicated that a radio frequency, the number of the histories ofcommunication of whose is great (for example, an amount of communicationon which is large), is a radio frequency in which communicationinterference is comparatively smaller in the connection base stationthat employs the radio frequency than in base stations in the vicinity.Therefore, the assignment of such a radio frequency for thecommunication with the connection base station is suitable.

Furthermore, because an amount of data that is accumulated is large whenit comes to a radio frequency that is frequently used in the past, thereis a high likelihood that this radio frequency will be selected as acandidate. There is a high likelihood that the radio frequency which isused frequently in the past will make communication between theconnection base station and the communication with terminal 100successful in the future as well. Therefore, terminal 100 can improvethe precision of communication in the communication with the connectionbase station.

Therefore, in the heterogeneous network, terminal 100 can reduce thenumber of times that the communication interference (intercellinterference) among a plurality of base stations 200 occurs, and cansuppress assignment processing a radio resource for data retransmissionfrom being frequently performed.

Accordingly, terminal 100 can exactly determine which radio frequencyhas to be assigned for which base station 200. Furthermore, terminal 100can reduce power consumption by terminal 100 when searching for basestation 200 that is connected to terminal 100, and can reduce the timeit takes to search for base station 200. Furthermore, terminal 100 canimprove the efficiency of assignment of or the efficiency of usage ofthe radio resource that is used for the communication with theconnection base station.

[Communication Environment of the Radio Communication System]

Next, a communication environment of radio communication system 10 isdescribed.

At this point, as an example, it is assumed that the connection basestation employs RAT 5. It is also decided that terminal 100 employs theRAT 5. Furthermore, it is assumed that eight usable radio frequenciesare present in RAT 5. The eight radio frequencies in RAT 5 are expressedas f_(5,1), f_(5,2), f_(5,3), f_(5,4), f_(5,5), f_(5,6), f_(5,7), andf_(5,8), respectively. For example, f_(5,1) indicates a first radiofrequency in RAT 5.

FIG. 7 is a schematic diagram illustrating an example of a locationrelationship between base station 200 and terminal 100. It is assumedthat base stations 200 (BS1 to BS9) that are illustrated in FIG. 7 arepresent in the vicinity of terminal 100 (terminal T) and that it ispossible that RAT 5 is employed.

In FIG. 7, base stations 200 (BS1 to BS6) that are surrounded by solidlines are base stations of a communications carrier to whom terminal 100subscribes. Base stations 200 (BS7 to BS9) that are surrounded by dottedlines are base stations of a communications carrier who is differentfrom the communications carrier to whom terminal 100 subscribes.

In FIG. 7, base station 200 as the connection base station is BS 4.However, although only base stations 200 that are present in thevicinity are considered, terminal 100 shares the eight radio frequenciesf_(5,1) to f_(5,8) with BS 1 to BS 9. Therefore, when terminal 100performs communication with BS 4, there is a likelihood that radiofrequencies will overlap which are in use by the other base stations, BS1 to BS 3 and BS 5 to BS 9, and that communication quality will bedegraded due to mutual interference.

As a comparative example, it is assumed that in order to alleviate thedegradation in the communication quality, each terminal detects thechannel quality of an in-use radio channel (for example, a radiofrequency that is employed by in-use RAT 5) and notifies a base stationof the detected channel quality. In this case, the terminal needs tomonitor the channel quality of the eight radio frequencies f_(5,1), tof_(5,8) in RAT 5. A result of the channel quality needs to be notifiedto the base station.

In the comparative example, it is also considered that a predeterminedbase station detects the channel quality of the radio circuit that is inuse by the base station of the same communications carrier. However, thebase station has difficulty integrating in an inclusive manner pieces ofinformation on circuit qualities of radio circuits that are in use bybase stations of a different communications carrier. In the future, in acase where it is possible that a plurality of different communicationscarriers assign the same radio frequency, a countermeasure against theinterference described above is further needed.

In contrast, in the present embodiment, terminal 100 derives theassignment candidate for the radio frequency according to the past usagehistory in which each radio frequency is used, and thus there is no needto take into consideration which radio frequency is assigned to otherbase stations 200. For this reason, terminal 100 does not need to takeinto account which communications carrier possess base station 200, andcan assign the radio frequency without interference to the connectionbase station with ease and precision.

In this manner, because terminal 100 assigns the radio frequencyaccording to the history of communication between terminal 100 and basestation 200, there is no need to detect channel quality information onthe radio frequency that is usable by each RAT. The channel qualityinformation, for example, includes a Signal to Interference Noises Ratio(SINR). Therefore, terminal 100 does not need to notify base station 200of the channel quality information described above.

More precisely, terminal 100 does not need to perform detection of thechannel qualities of the radio frequencies of which the number is thesame as the number of the radio frequencies that are employed by the RATthat is present in the heterogeneous network. For this reason, terminal100 can reduce the processing load and the processing time for detectingthe channel quality of each radio frequency. Furthermore, the connectionbase station does not need to frequently perform delivery of the channelquality information on each radio frequency, between connection basestation itself and terminal 100, and can reduce the processing load andthe processing time relating to the notification of the channel qualityof each radio frequency.

In this manner, terminal 100 stores history database T2 that retains theinformation that is the history of communication on every radiofrequency relating to the communication with the connection basestation. After the determination of the connection base station,terminal 100, for example, determines the priority levels, in order ofdecreasing an amount of communication on a radio frequency as thehistory of communication that is retained in history database T2, anddetermines whether or not a radio resource (a radio frequency or a RB)is assigned. Accordingly, terminal 100 can determine the radio resourcethat is used for communication, with base station 200 retaining historydatabase T2.

OTHER EMBODIMENTS

The first embodiment is described above as an example of the technologyin the present disclosure. However, the technology in the presentdisclosure is not limited to the present disclosure, and can apply alsoto an embodiment than results from performing change, substitution,addition, omission, and the like.

In the first embodiment, history database T1 is described as retainingthe information that is the history of communication with the connectionbase station during a past fixed period of time, but the informationthat is the history of communication may be accumulated regardless of aperiod of time. Furthermore, history database T2 is described asretaining the usage history of the radio frequency during the past fixedperiod of time, but the information that is the usage history may beaccumulated.

In the first embodiment, in terminal 100, base station locator 104locates the connection candidate base station based on history databaseT1, and then, radio resource assignment manager 105 may assign the radiofrequency that is used for the communication with base station 200,using a known method. Furthermore, in terminal 100, base station locator104 locates the connection candidate base station using a known method,and then radio resource assignment manager 105 may assign the radiofrequency that is used for the communication with base station 200,based on history database T2.

In the first embodiment, as an example, an accumulation value of theamount of communication in every location in which terminal 100 ispresent is described as being used as the information that is thehistory of communication with base station 200, but information that isanother history of communication may be used. The information that isanother usage history, for example, includes a total amount of timetaken for the communication with base station 200 (a total amount ofconnection time) and the number of times of communication (the number oftimes of connection) with base station 200. For example, the larger thetotal amount of communication time described above and the greater thenumber of times of communication described above, the higher thepriority level, based on which base station 200 is selected as theconnection base station.

In the first embodiment, as an example, the accumulation value of theamount of communication on every radio frequency is described as theinformation that is the usage history of the radio resource, butinformation that is another usage history may be used. The informationthat is another usage history, for example, includes a total amount ofcommunication time (a total amount of connection time) between terminal100 and base station 200, which uses the radio frequency, and the numberof times of communication (the number of times of connection) betweenterminal 100 and the communication with base station 200, which uses theradio frequency. For example, the larger the total amount ofcommunication time described above and the greater the number of timesof communication described above, the higher the priority level based onwhich the radio frequency is selected.

As disclosed in the reference patent literature, Japanese PatentUnexamined Publication No. 2013-232815, history databases T1 and T2 maybe provided in a distinguished manner from various points of view. Forexample, history databases T1 and T2 may be provided, in a distinguishedmanner, for every time span for which the radio resource is assigned orfor every transmission power of base station 200. Furthermore, historydatabases T1 and T2 may be provided, in a distinguished manner, forevery uplink 21 and every downlink 22. Furthermore, with other knownmethods, history databases T1 and T2 may be provided. Accordingly,terminal 100 can determine the connection candidate base station or theassignment candidate for the radio frequency according to the history ofcommunication or the usage history that reflects various tendencies.

In the first embodiment, as an example, by managing the usage history ofthe amount of communication on every radio frequency, terminal 100 isdescribed as determining as the radio resource the candidates for theradio frequency that is used for the communication with base station200. By managing not only the radio frequency but also the usage historyof the amount of communication in every time slot (every section on thetime axis) on a certain radio frequency, terminal 100 may determine acandidate for a time slot that is to be used for the communication withbase station 200. Furthermore, by managing the usage history of theamount of communication in every combination of the radio frequency andthe time slot (section in the time axis) on the radio frequency,terminal 100 may determine a candidate for the combination of the radiofrequency and the time slot, which is the radio resource that is usedfor the communication with base station 200.

For example, in a case where one radio frequency (f1) is present andwhere the one radio frequency is divided into 16 time slots (TSs), formanagement, terminal 100 may update the usage history of the past amountof communication on each of 16 radio resources, f1-TS1, f1-TS2, and soforth up to f1-TS16. Accordingly, terminal 100 can segregate radioresources (time slots here) into ones for the neighboring base stations.

Furthermore, for example, in a case where two radio frequencies (f1 andf2) are present and where each radio frequency is divided into 10 timeslots, for management, terminal 100 may update the usage history of thepast amount of communication on each of 20 radio resources, f1-TS1,f1-TS2 and so forth up to f1-TS10, and f2-TS1, f2-TS2 and so forth up tof2-TS10. Accordingly, terminal 100 can segregate radio frequencies(combinations of the radio frequency and the time slot) into ones forthe neighboring base stations.

In the first embodiment, processor 150 may physically employ anyconfiguration. However, if a processor that is programmable is used,because details of processing can be changed with a change in a program,the degree of freedom in designing processor 150 can be increased.Furthermore, processor 150 may be configured into one semiconductorchip, and may be physically configured into a plurality of semiconductorchips. In a case where processor 150 is configured into the plurality ofsemiconductor chips, each control in the first embodiment may berealized as a semiconductor chip. In this case, it can be consideredthat one processor 150 is configured into these semiconductor chips.Furthermore, processor 150 may be configured into a unit (a capacitor orthe like) that has a different function than the semiconductor chip.Furthermore, one chip may be configured in such a manner that a functionwhich processor 150 has and a function other than the function thatprocessor 150 has are realized.

(Outline of the Embodiment in the Present Disclosure)

As described above, terminal 100 in the embodiment described abovecommunicates with base station 200 through a network in which aplurality of radio communication scheme are present for use in a mixedmanner. Terminal 100 includes processor 150 and an antenna. Processor150 acquires the location information of terminal 100, and based on thelocation information of terminal 100 and on the information that is thehistory of communication with base station 200 in every location inwhich terminal 100 is present, locates a connection base station as basestation 200 that communicates the user data with terminal 100, among aplurality of base station 200. Through the antenna, the user data iscommunicated between terminal itself and the connection base station.

Terminal 100 is an example of a radio communication terminal. Basestation 200 is an example of a radio base station apparatus. Theantenna, for example, is transmission antenna 108 or reception antenna109.

Accordingly, terminal 100 can selectively base station 200 as acommunication destination of the user data in the heterogeneous networkthat has a different radio communication scheme or satisfiescharacteristics of different base station 200. For this reason, terminal100 can reduce the inconvenience of selecting base station 200.Therefore, terminal 100 can reduce the power consumption by terminal 100when searching for base station 200, and can reduce the time it takes tosearch for base station 200.

Furthermore, processor 150 may locate a connection base station,preferentially base station 200 that has many of the histories ofcommunication.

Accordingly, because it is possible that the connection base stationthat has a high likelihood of succeeding in the communication of theuser data, terminal 100 can improve the precision of the communicationof the user data.

Furthermore, the information that is the history of communication mayinclude an amount of data communication that takes place duringcommunication with base station 200, the data communication time forwhich the communication with base station 200 is performed, or thenumber of times that the data communication with base station 200 isperformed.

Furthermore, terminal 100 may include memory 160 in which theinformation that is the history of communication with base station 200in every location in which terminal 100 is present is stored. Based onthe history of communication relating to the communication of the userdata between the connection base station to which the user data iscommunicated through the antenna, and the connection base station,processor 150 may update the information that is the history ofcommunication which is accumulated in memory 160.

Accordingly, whenever terminal 100 communicates the user data with basestation 200, the latest history of communication with the connectionbase station can be reflected. Accordingly, terminal 100 can improve theefficiency of the selection of the connection base station.

Furthermore, the base station assignment method in the embodimentdescribed above is a base station assignment method in which terminal100 communicates with base station 200, through a network in which aplurality of radio communication schemes are present for use in a mixedmanner. In this method, the location information of terminal 100 isacquired, and based on the location information of terminal 100 and onthe information that is the history of communication with base station200 in every location in which terminal 100 is present, a connectionbase station is located as base station 200 that communicates the userdata with terminal 100, among a plurality of base station 200 and theuser data is communicated between terminal 100 and the connection basestation.

Accordingly, terminal 100 can selectively base station 200 as acommunication destination of the user data in the heterogeneous networkthat has a different radio communication scheme or satisfiescharacteristics of different base station 200. For this reason, terminal100 can reduce the inconvenience of selecting base station 200.Therefore, terminal 100 can reduce the power consumption by terminal 100when searching for base station 200.

Furthermore, in terminal 100 in the embodiment described above,processor 150 locates a connection base station as base station 200 thatcommunicates the user data with terminal 100, among a plurality of basestations 200. Based on the information that is the usage history of theradio frequency relating to the communication of the user data withevery base station 200, processor 150 assigns the radio frequencyrelating to the communication of the user data between the connectionbase station and terminal 100. Through the antenna, the user data iscommunicated between terminal 100 itself and the base station using theassigned radio frequency.

Accordingly, terminal 100 can reduce the number of times that thecommunication interference between terminal 100 and base station 200 inthe vicinity occurs. For this reason, terminal 100 reduces the number oftimes that a radio source assignment operation is repeated, and thus canshorten the time it takes to assign the radio resource to terminal 100or base station 200. More precisely, terminal 100 can improve theefficiency of the assignment of the radio resource. Furthermore,terminal 100 can improve the efficiency of the usage of the radioresource without dividing the frequency in advance among a plurality ofbase stations 200.

In some cases, base station 200 can be configured only with the basestation of the same communications carrier, or can be configured in sucha manner that the same radio resource is shared among base stations of aplurality of different communications carriers. Even with theseconfigurations, terminal 100 can determine the assignment of the radioresource without a plurality of base stations 200 sharing informationwith each other.

Furthermore, for every base station 200, terminal 100 may include memory160, in which the information that is the usage history of the radiofrequency according to the communication of the user data isaccumulated. Based on the radio frequency that is used for thecommunication of the user data through the antenna, and on the usagehistory of the radio frequency, processor 150 may update the informationthat is the usage history which is accumulated in memory 160.

Accordingly, whenever terminal 100 communicates the user data with basestation 200, the latest usage history of the radio resource can bereflected. Accordingly, terminal 100 can improve the efficiency of theassignment of or the efficiency of the usage of the radio resource.

Furthermore, processor 150 may assign the radio frequency,preferentially the radio frequency that has many of the usage histories.

Accordingly, because the radio frequency that has a high likelihood ofsucceeding in the communication of the user data is allocable, terminal100 can improve the precision of the communication of the user data.

The information that is the usage history may include an amount of datacommunication that uses the radio frequency, the data communication timefor which the radio frequency is used, or the number of times that thedata communication which uses the radio frequency is performed.

Furthermore, based on the information that is the usage history of theradio frequency relating to the communication of the user data withevery base station 200, processor 150 may assign the assignmentcandidate for the radio frequency relating to the communication of theuser data between the connection base station and terminal 100. In acase where it is impossible that the radio frequency that is theassignment candidate is assigned, processor 150 may assign another radiofrequency. Through the antenna, the user data may be communicated usingthe another radio frequency.

Accordingly, even in a case where no radio frequency that is theassignment candidate is unoccupied, terminal 100 can re-designateanother radio frequency, and can improve the likelihood that terminal100 and the connection base station will be able to communicate the userdata.

Furthermore, in a case where it is impossible that the radio frequencythat is the assignment candidate is assigned, processor 150 may changethe connection base station to another connection base station.

Accordingly, even in the case where no radio frequency that is theassignment candidate is unoccupied, terminal 100 can re-designateanother connection base station, and can improve the likelihood thatterminal 100 and the connection base station will be able to communicatethe user data.

Furthermore, the frequency assignment method in the embodiment describedabove is a frequency assignment method in terminal 100 between terminal100 itself and base station 200, through a network in which a pluralityof radio communication schemes are present for use in a mixed manner. Inthe method, the connection base station as base station 200, among aplurality of base stations 200, that communicates the user data withterminal 100 is located, the radio frequency relating to thecommunication of the user data between the connection base station andterminal 100 is assigned based on the information that is the usagehistory of the radio frequency according to the communication of theuser data with every base station 200, and the user data is communicatedwith the connection base station using the assigned radio frequency.

Accordingly, terminal 100 can reduce the number of times that thecommunication interference between terminal 100 and base station 200 inthe vicinity occurs. For this reason, terminal 100 reduces the number oftimes that a radio source assignment operation is repeated, and thus canshorten the time it takes to assign the radio resource to terminal 100or base station 200. More precisely, terminal 100 can improve theefficiency of the assignment of the radio resource. Furthermore,terminal 100 can improve the efficiency of the usage of the radioresource without dividing the frequency in advance among base stations200.

INDUSTRIAL APPLICABILITY

The present disclosure is useful for a radio communication terminal, abase station assignment method, and the like that can reduce powerconsumption by the radio communication terminal when searching for theradio base station apparatus that is to be connected to the radiocommunication terminal, and that can reduce the time it takes to searchfor the radio base station apparatus.

REFERENCE MARKS IN THE DRAWINGS

10 RADIO COMMUNICATION SYSTEM

21 UPLINK

22 DOWNLINK

50 GPS SATELLITE

100 TERMINAL

101 GPS ANTENNA

102 GPS RECEPTION

103 LOCATION INFORMATION GENERATOR

104 BASE STATION LOCATOR

105 RADIO RESOURCE ASSIGNMENT MANAGER

106 TRANSMISSION PACKET GENERATOR

107 RADIO TRANSMITTER

108 TRANSMISSION ANTENNA

109 RECEPTION ANTENNA

110 RADIO RECEIVER

111 RECEPTION PACKET DECODER

200 BASE STATION

T1, T2 HISTORY DATABASE

1. A radio communication terminal that communicates with a radio basestation apparatus through a network in which a plurality of radiocommunication schemes are present for use in a mixed manner, theterminal comprising: a processor; and an antenna, wherein the processoracquires location information of the radio communication terminal,wherein the processor locates a connection base station as a radio basestation apparatus that communicates user data with the radiocommunication terminal, among a plurality of the radio base stationapparatuses, based on the location information of the radiocommunication terminal and on information that is the history ofcommunication with the radio base station apparatus in every location inwhich the radio communication terminal is present, and wherein throughthe antenna, the user data is communicated between the radiocommunication terminal and the connection base station.
 2. The radiocommunication terminal of claim 1, wherein the processor locates theconnection base station, preferentially a radio base station apparatusthat has many of the communication histories.
 3. The radio communicationterminal of claim 1, wherein the information that is the history ofcommunication includes an amount of data communication that takes placeduring communication with the radio base station apparatus, the datacommunication time for which the communication with the radio basestation apparatus is performed, or the number of times that data stationcommunication with the radio base apparatus is performed.
 4. The radiocommunication terminal of claim 1, further comprising: a memory in whichthe information that is the history of communication with the radio basestation apparatus in every location in which the radio communicationterminal is present is accumulated, wherein the processor updates theinformation that is the history of communication which is accumulated inmemory, based on the history of communication relating to thecommunication of the user data between a connection base station towhich the user data is communicated through the antenna and theconnection base station
 5. A base station assignment method for use in aradio communication terminal that communicates with a radio base stationapparatus through a network in which a plurality of radio communicationschemes are present for use in a mixed manner, the method comprising:acquiring location information of the radio communication terminal;locating a connection base station as a radio base station apparatusthat communicates user data with the radio communication terminal, amonga plurality of the radio base station apparatuses, based on the locationinformation of the radio communication terminal and on information thatis the history of communication with the radio base station apparatus inevery location in which the radio communication terminal is present; andcommunicating the user data between the radio communication terminal andthe connection base station.